1. Field of the Invention
The present invention relates to an endoscope that has a bending section formed with a fluid-pressure actuator as the distal part of an elongated insertion unit which is inserted into a lumen, and that is adapted to industrial or medical use.
2. Description of the Related Art
In general, endoscopes adaptable to industrial or medical use have an insertion unit that is inserted into a lumen. A type of endoscope having a soft and elongated insertion unit has a bending section formed as the distal part of the insertion unit. When the bending section is bent, for example, an observing direction can be set to any direction.
As far as endoscopes for industrial use are concerned, the insertion unit is requested to be inserted 30 m or more. In this case, if a bending mechanism is of a type having angling wires that are pulled in order to move the bending section of an endoscope, a user may find it hard to bend the bending section as he/she intends to. This is because sliding resistance or the like occurs between the angling wires and other members. A proposal has been made of an endoscope having a fluid-pressure actuator, which bends with supply of fluid such as air, as the bending mechanism for a bending section.
For example, U.S. Pat. No. 5,577,992 has disclosed a bending section of an endoscope that is finely thin and can be bent at a large bending angle while exhibiting a small radius of curvature at a certain point. The bending section of the endoscope has a member, which restricts expansion of a stretchable and contractile member, wound about the stretchable and contractile member, whereby expansion of the stretchable and contractile member in a radial direction is restricted. Consequently, a pressurized pressure chamber (fluid chamber in the present embodiment) stretches largely forwards and eventually bends largely.